ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: Building, Iron and steel
- All Subjects: Plastic deformation
- Creators: Mobasher, Barzin
Description
Tall building developments are spreading across the globe at an ever-increasing rate (www.ctbuh.org). In 1982, the number of ‘tall buildings’ in North America was merely 1,701. This number rose to 26,053, in 2006. The global number of buildings, 200m or more in height, has risen from 286 to 602 in the last decade alone. This dissertation concentrates on design optimization of such, about-to-be modular, structures by implementing AISC 2010 design requirements. Along with a discussion on and classification of lateral load resisting systems, a few design optimization cases are also being studied. The design optimization results of full scale three dimensional buildings subject to multiple design criteria including stress, serviceability and dynamic response are discussed. The tool being used for optimization is GS-USA Frame3D© (henceforth referred to as Frame3D). Types of analyses being verified against a strong baseline of Abaqus 6.11-1, are stress analysis, modal analysis and buckling analysis.
The provisions in AISC 2010 allows us to bypass the limit state of flexural buckling in compression checks with a satisfactory buckling analysis. This grants us relief from the long and tedious effective length factor computations. Besides all the AISC design checks, an empirical equation to check beams with high shear and flexure is also being enforced.
In this study, we present the details of a tool that can be useful in design optimization - finite element modeling, translating AISC 2010 design code requirements into components of the FE and design optimization models. A comparative study of designs based on AISC 2010 and fixed allowable stresses, (regardless of the shape of cross section) is also being carried out.
The provisions in AISC 2010 allows us to bypass the limit state of flexural buckling in compression checks with a satisfactory buckling analysis. This grants us relief from the long and tedious effective length factor computations. Besides all the AISC design checks, an empirical equation to check beams with high shear and flexure is also being enforced.
In this study, we present the details of a tool that can be useful in design optimization - finite element modeling, translating AISC 2010 design code requirements into components of the FE and design optimization models. A comparative study of designs based on AISC 2010 and fixed allowable stresses, (regardless of the shape of cross section) is also being carried out.
ContributorsUnde, Yogesh (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2016
Description
Composite materials are now beginning to provide uses hitherto reserved for metals in structural systems such as airframes and engine containment systems, wraps for repair and rehabilitation, and ballistic/blast mitigation systems. These structural systems are often subjected to impact loads and there is a pressing need for accurate prediction of deformation, damage and failure. There are numerous material models that have been developed to analyze the dynamic impact response of polymer matrix composites. However, there are key features that are missing in those models that prevent them from providing accurate predictive capabilities. In this dissertation, a general purpose orthotropic elasto-plastic computational constitutive material model has been developed to predict the response of composites subjected to high velocity impacts. The constitutive model is divided into three components – deformation model, damage model and failure model, with failure to be added at a later date. The deformation model generalizes the Tsai-Wu failure criteria and extends it using a strain-hardening-based orthotropic yield function with a non-associative flow rule. A strain equivalent formulation is utilized in the damage model that permits plastic and damage calculations to be uncoupled and capture the nonlinear unloading and local softening of the stress-strain response. A diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, in composites it has been found that loading in one direction can lead to damage in multiple coordinate directions. To account for this phenomena, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. The overall framework is driven by experimental tabulated temperature and rate-dependent stress-strain data as well as data that characterizes the damage matrix and failure. The developed theory has been implemented in a commercial explicit finite element analysis code, LS-DYNA®, as MAT213. Several verification and validation tests using a commonly available carbon-fiber composite, Toyobo’s T800/F3900, have been carried and the results show that the theory and implementation are efficient, robust and accurate.
ContributorsHoffarth, Canio (Author) / Rajan, Subramaniam D. (Thesis advisor) / Goldberg, Robert (Committee member) / Neithalath, Narayanan (Committee member) / Mobasher, Barzin (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2016